1. Field of the Invention
The present invention relates to a multilayer board having a structure in which a plurality of resin base materials made from a thermoplastic resin are laminated.
2. Description of the Related Art
Hitherto, a multilayer board has been known in which in a state where a plurality of resin base materials made from a thermoplastic resin are stacked, the resin base materials are fused thus to be joined together (e.g., see International Publication No. WO 2012/147484).
International Publication No. WO 2012/147484 discloses a multilayer board which includes: a flexible portion having a small thickness and flexibility; and rigid portions having a large number of laminated resin sheets and a large thickness. In the multilayer board, a first resin sheet extends over the entire area of the flexible portion and the rigid portions, and in each rigid portion, second resin sheets which form an outer surface of the multilayer board are laminated such that the first resin sheet is interposed therebetween. Thus, in the flexible portion, only the first resin sheet is disposed, so that the thickness of the flexible portion is small. Meanwhile, in each rigid portion, the second resin sheets are disposed so as to be overlaid on the first resin sheet, so that the thickness of the rigid portion is large.
However, in International Publication No. WO 2012/147484, it is conceivable that in bending (deflecting) the flexible portion, a load is applied to a step portion between each rigid portion having a large thickness and the flexible portion having a small thickness and an end portion of the second resin sheet that is located at the step portion is peeled from the first resin sheet.